Bulk container

ABSTRACT

A container especially suitable for bulk materials and including a cardboard tubular sleeve having its lower edge portion positioned in upwardly opening groove means on a plastic pallet. The tubular sleeve is a sleeve assembly comprising inner and outer tubular sleeves respectively formed of first and second corrugated cardboard structures with the inner sleeve positioned telescopically within the outer sleeve and with the outer annular surface of the inner sleeve secured to the inner annular surface of the outer sleeve to form a composite sleeve assembly having a thickness approximating the width of the groove means on the pallet. An auxiliary cardboard sheet is secured to the outboard surface of the outer tubular sleeve and an auxiliary cardboard sheet is secured to the inboard surface of the inner cardboard sleeve. A vinyl sheet is adhesively secured to the auxiliary cardboard sheet of the outer tubular sleeve and a further vinyl sheet is adhesively secured to the auxiliary cardboard sheet of the inner tubular sleeve so that, with the inner and outer tubular sleeves telescopically assembled, the vinyl sheets form the inner and outer annular surfaces of the composite sleeve assembly. The vinyl sheets also cover the upper and lower annular end edges of the sleeve assembly so as to make the sleeve assembly substantially moisture impervious. Also disclosed is a method for folding the sleeve assembly into a totally flat collapsed configuration to facilitate storage and shipment.

RELATED APPLICATION

This is a division of application Ser. No. 650,034, filed on Feb. 4,1991, now U.S. Pat. No. 5,133,460, which is a continuation-in-part ofU.S. patent application Ser. No. 489,331, filed on Mar. 5, 1990, nowU.S. Pat. No. 4,989,731 which is continuation-in part of patentapplication Ser. No. 219,042, filed Feb. 14, 1988 now U.S. Pat. No.4,936,451 which is a continuation-in part of U.S. patent applicationSer. No. 080,230, filed on Jul. 28, 1987, now U.S. Pat. No. 4,765,252which is a continuation of U.S. patent application Ser. No. 858,524,filed on Apr. 23, 1986, now abandoned, which is a continuation of U.S.patent application Ser. No. 642,778, filed on Aug. 21, 1984, nowabandoned.

FIELD OF THE INVENTION

This invention relates to containers and more particularly to containersthat are especially suitable for use with bulk materials.

Although a plurality of diverse containers are available in themarketplace, few if any of the available containers are totally suitablefor use in shipping and storing bulk materials. Bulk materials posepeculiar requirements with respect to containers since their flowpatterns and their angle of repose create extremely high burstingpressures especially in the lower regions of the material within thecontainer. Containers for discrete, free standing articles, bycomparison, need only contain the discrete articles, and in general neednot deal with the extremely high bursting pressures present in the caseof bulk materials.

SUMMARY OF THE INVENTION

This invention is directed to the provision of an improved container.

More specifically, this invention is directed to the provision of a bulkcontainer which is simple and inexpensive in design and yet whichsuccessfully withstands the extremely high burst pressures generated bystored bulk materials.

The invention container is of the type comprising a rigid plastic palletand a tubular sleeve adapted to be supported in upstanding fashion onthe upper face of the pallet to form the container. According to theinvention, the wall of the sleeve has a sandwich cross-sectionalconstruction including an inner plastic layer, a central cardboardlayer, and an outer plastic layer. This sandwich construction for thesleeve allows the use of inexpensive and readily available cardboard andplastic materials to form the sleeve while providing a strong moistureimpervious construction for the sleeve.

According to a further feature of the invention, the central cardboardlayer comprises a corrugated cardboard layer. This arrangement allowsthe use of readily available and inexpensive corrugated cardboardmaterials to form the sleeve.

According to a further feature of the invention, the inner and outerplastic layers comprise vinyl layers. This arrangement allows the use ofreadily available vinyl sheets to be employed in combination with thereadily available corrugated cardboard to form the sleeve assembly.

According to a further feature of the invention, the plastic layersfurther cover the upper and lower annular end edges of the sleeve. Thisarrangement provides a moisture impervious construction for the sleeveso as to allow outdoor storage of the sleeve and enhance the usabilityand reusability of the sleeve in applications, such as food handling,where sanitation is important.

According to a further feature of the invention, the central cardboardlayer comprises inner and outer tubular sleeves respectively formed asfirst and second corrugated cardboard structures with the inner sleevepositioned telescopically within the outer sleeve and with the outerannular surface of the inner sleeve secured to the inner annular surfaceof the outer sleeve to form a composite sleeve assembly. Thisconstruction provides a sleeve assembly employing simple, inexpensiveplastic and cardboard materials and yet which is able to withstand theextremely high bursting pressures generated by stored bulk materials.

According to a further feature of the invention, the inner and outercardboard structures each comprise two cardboard panels arrangedend-to-end; one cardboard panel of the outer cardboard structure issecured to one panel of the inner cardboard structure in staggeredrelation and the secured panels are formed into a first partial sleeveassembly; the other cardboard panel of the outer cardboard structure issecured to the other panel of the inner cardboard structure in staggeredrelation and the secured panels are formed into a second partial sleeveassembly; and the first and second partial sleeve assemblies are broughttogether in interfitting fashion to form the sleeve assembly. Thisarrangement provides a simple and efficient method of constructing thesleeve assemblies and results in a sleeve assembly with staggered seamsto augment the overall strength of the sleeve assembly.

According to a further feature of the invention, the pallet includesdownwardly opening tunnels extending across the lower face thereof forreceipt of the forks of a forklift truck and groove means are definedaround the periphery of the upper face of the pallet over the tunnelsfor receipt of the lower edge of the sleeve. This arrangement provides asimple and effective means of providing means for receipt of the loweredge of the sleeve and simultaneously provides the requisite tunnels forreceipt of the forks of a forklift truck.

According to a further feature of the invention, coacting means areprovided to releasably secure the sleeve to the pallet, the coactingmeans comprise slots in the lower peripheral edge of the sleeve and aplurality of latch members mounted on the upper face of the pallet overthe tunnels, and the vinyl sheets forming the inner and outer plasticlayers of the sleeve assembly further serve to provide a lining for theslots in the sleeve. This arrangement further augments the moistureimpervious character of the sleeve and augments the durability of theslots.

According to a further feature of the invention, a method is providedfor selectively creasing the sleeve material at longitudinally spacedlocations so as to facilitate the folding of the sleeve material into atubular configuration and so as to allow the sleeve to be readily foldedthrough 180° into a totally flat configuration to facilitate storage andshipping of the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the invention container;

FIG. 2 is a top plan view of a sleeve assembly utilized in the inventioncontainer;

FIG. 3 is a top plan view of a pallet utilized in the inventioncontainer;

FIG. 4 is a bottom plan view of a lid utilized in the inventioncontainer;

FIG. 5 is a fragmentary cross sectional view illustrating thecooperative interaction of the invention sleeve assembly, the inventionpallet, and the invention lid;

FIG. 6 is a fragmentary cross sectional view illustrating details of theinvention sleeve assembly;

FIG. 7 is a fragmentary view illustrating further details of theinvention sleeve assembly;

FIGS. 8-10 are detailed views illustrating a latch mechanism employed inthe invention container;

FIG. 11 illustrates steps in the methodology employed in forming theinvention container;

FIG. 12 illustrates further details of one of the steps of themethodology illustrated in FIG. 11;

FIGS. 13-21 illustrate apparatus and steps employed in an alternatemethodology for forming the invention container.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The container 10 seen in FIG. 1 is a composite plastic and cardboarddesign employing a pallet 14, an upper unit or lid 16, and a sleeveassembly 17.

The pallet 14 and lid 1 6 are formed of a plastic material and arepreferably formed of sheets of organic polymeric material such aspolyethylene. Pallet 14 and lid 16 preferably employ a twin sheetconstruction employing two sheets which are vacuum formed and then fusedor knitted together at various points to add structural rigidity.

Pallet 14 is generally planar and includes a flat platform structure 18,defining a flat upper load face 20, and a plurality of hollow legsextending downwardly from platform structure 18 and opening in upperface 18. As shown, corner legs 22 are provided at each corner of thepallet, intermediate legs 24 are provided at an intermediate locationalong each side of the pallet, and a central leg 26 is providedcentrally of the pallet. Legs 2, 24 and 26 will be seen to cooperate todefine tunnels or indentations 28 extending transversely andlongitudinally across the lower face of the pallet to provide relievedaccess areas for receiving the forks of a forklift truck or the like. Asa consequence, the container may be lifted and moved by conventionalwarehousing equipment.

Pallet 14 includes an upper vacuum formed sheet 30 forming the upperface 20 of the platform structure 18 and a lower vacuum formed sheet 32forming the lower face 34 of the platform structure 18. Upper sheet 30includes a plurality of downwardly extending protrusions 30a which areknitted or fused to upwardly extending protrusions 32a on lower sheet 32to form the platform structure 18. Further details of this protrusionstructure are shown in U.S. Pat. No. 4,879,956 assigned to the assigneeof the present application. Sheets 30 and 32 also include leg portions30b,32b, respectively, which are fused or knitted together to form thelegs 22, 24 and 26.

Upper sheet 30 further includes a plurality of circumferentially spacedupwardly opening U-shaped edge portions 30c positioned over each tunnel28 and coacting to define a plurality of upwardly opening groove means40 spaced circumferentially around the periphery of the pallet. Sheets30,32 also include outer upwardly extending portions 30d,32c fusedtogether to form a continuous rim 42 extending around the periphery ofthe pallet. Rim 42 is configured to define side wall portions 42a alongthe four sides of the pallet and angled or rounded corner portions 42bat each corner of the pallet extending on a bias across the corners ofthe pallet between adjacent rim sides 42a.

The various fuse or knit lines as between the upper sheet 30 and thelower sheet 32 are indicated by dash lines in the drawings.

A plurality of latch assemblies 44 are provided on pallet 14 atcircumferentially spaced locations thereabout. For example, a pair oflatch assemblies 44 may be provided along two opposite sides of thepallet with each latch assembly located over a tunnel 28 and therefor inassociation with a groove means 40. Each latch assembly 44 includes alatch member 46 mounted on the pallet for detented sliding movementbetween a retracted position in which the related sleeve assembly edgeis free to enter or leave the related groove means 40 and an extended orlocking position in which the tip of the latch member extends across thegroove means.

Latch members 46 are preferably formed of the same plastic material asthe pallet and each includes a main body portion 46a in the form of aelongated plate and a tubular handle or actuator portion 46b formedintegrally with main body portion 46a adjacent one end thereof. Latchmembers 46 are slidably positioned between the upper and lower sheets30,32 of the pallet. Specifically, the upper and lower sheets areconfigured to define slideways 48 extending perpendicularly inwardlyfrom groove means 40 and opening at their outboard ends 50 in thesegroove means. Latch members 46 are positioned in slideways 48 with latchhandle portions 46b received in detent structures 52 formed integrallywith the lower sheet 32 of the pallet and disposed in downwardly openinghollows or depressions 54 formed in the lower sheet at the outboard endsof the tunnels 28 between adjacent pallet legs. Detent structures 52have a generally figure eight formation with the neck 52a at thejuncture of the two halves 52b,52c of the detent dimensioned to beslightly smaller than the external diameter of latch handle portion 46dso that the handle portion 46b passes snappingly between detent halves42b and 42c as the latch moves between its retracted and extendedpositions in response to a pull or push exerted by a finger or fingersinserted into the open end of handle portion 46b.

Pallet 14 is preferably formed in a twin sheet press in which the twosheets 30,32 are individually vacuum formed and thereafter fused orknitted together to form the double wall structure. The pallet alsopreferably includes a plurality of tubular steel members 56, ofrectangular cross section, positioned between the upper and lower sheets30,32 and extending in parallel spaced relation across the full width ofthe pallet to augment the structural rigidity of the pallet.

Lid 16 is a planar twin sheet vacuum formed structure and is devoid ofthe legs of the pallet 14 and thereby devoid of the tunnels formedbetween the legs of the pallet. Lid 16 defines a rim 58 extendingcontinuously around the periphery of the lid and defining the outer wallor border of a downwardly opening groove 60 extending continuouslyaround the periphery of the lid. Rim 58 is configured to define sidewall portions 58a along the four sides of the lid and angled or roundedcorner portions 58b at each corner of the lid extending on a bias acrossthe corners of the lid between adjacent lid sides 58a.

Lid 16 further includes latch assemblies 44 on the lower face of the lididentical to the latch assemblies utilized on pallet 14. The latchassemblies 44 provided on the lower face of lid 16 correspond in numberand circumferential positioning to the latch assemblies provided on theupper face of the pallet 14. The latch members 46 of the lid latchassemblies are positioned between a retracted position in which they aredisposed inboard of the groove 60 and an extended latching position inwhich they extend across the groove.

Sleeve assembly 17 is formed from a pair of inner cardboard panels orstrips 70,71 and a pair of outer cardboard panels or strips 72,73.Panels 70-73 are preferably formed of three-ply corrugated material suchas is commercially available from Tri-Wall Containers Inc. Each panel70-73 is formed in known manner of a plurality of flat primary cardboardsheets 75 interspersed with and adhesively secured to a plurality ofcorrugated cardboard sheets 76 with flat primary sheets 75 disposed onthe inner and outer surfaces respectively of the panel so as to form amulti-layer sandwich construction. In addition, a flat auxiliarycardboard sheet 78 is secured to the inboard face of inner panels 70,71and a flat auxiliary cardboard sheet 80 is secured to the outboard faceof outer panels 72,73.

By way of example, auxiliary sheets 78,80 and the sheets 75 forming theouter faces of each panel may have a weight of 96 pounds per 1000 squarefeet and a thickness of 0.026 inches; intermediate sheets 75 may have aweight of 69 pounds per 1000 square feet and a thickness of 0.019inches; and corrugated sheets 76 may have a weight of 33 pounds per 1000square feet and a thickness of 0.011 inches.

Panels 70-73 are configured along their lower edges in a manner to matchthe configuration of the pallet 14. Specifically, a plurality ofcut-outs 70a, 71a, 72a, 73a are provided in circumferentially spacedfashion around the lower peripheral edge of the panels to define aplurality of legs 70b, 71b, 72b, 73b configured to fit respectivelywithin the hollow legs 22, 24 and 26 of the pallet with the edges 70c,71c, 72c, 73c at the tops of the cutouts positioned in groove means 40defined by the pallet.

A plurality of slots or apertures 74 are provided at circumferentiallyspaced locations along the upper edge portions of panels 70-73 and acorresponding plurality of slots or apertures 77 are provided along thelower peripheral edges of panels 70-73 proximate and above edges 70c,71c, 72c, 73c.

The methodology of performing the invention sleeve assembly is seen inFIG. 11. Specifically, FIGS. 11(a)-11(j) illustrate the formation of theouter panel 72; FIGS. 11(k) and 11(l) illustrate the combination ofouter panel 72 with inner panel 70 to form a panel subassembly; FIGS.11(m) and 11(n) illustrate the formation of first and second partialsleeve assemblies 86 and 88; and FIGS. 11(p) and 11(q) illustrate thecombining of the partial sleeve assemblies 86 and 88 to form the finalsleeve assembly 17.

According to the invention methodology, a sheet or panel 72 of standardtriple wall corrugated construction is provided including flat sheets 75interspersed with corrugated sheets 76; an auxiliary or supplementalcardboard sheet 80 is adhesively secured to the outer face of panel 72so as to combine with the outer sheet 75 to provide a reinforced outerskin for the panel; the panel is suitably die cut to provide slots 74,77and cutouts 72a; spray guns 90 are utilized to adhesively spray theinner and outer faces of the panel with a heat activated cement (suchfor example as the type available from PPG Adhesives and Solvents ofMadison Heights, Mich. as Part No. HC7111) to provide a cement coating72d entirely covering the inner and outer faces of the panel; a sheet ofvinyl material 82 is heated and applied in a back forming vacuumoperation (see also FIG. 12) to the outer face of the panel to form avinyl coating entirely covering the outer face of the panel andextending over the upper and lower and left and right end edges of thepanel and lining the apertures 74,77 of the panel; heat is applied tothe inner face of panel 72 and to the inner face of panel 70 (which hasbeen formed in the same manner as panel 72, according to the stepsillustrated in FIGS. 11(a)-11(j), to include auxiliary supplementalcardboard sheet 78 and outer sheet of vinyl material 82) to activate thecement coating 72(d),70(d) and the panel interfaces are pressed togetherto form a panel subassembly with panels 70 and 72 staggered so as toform a free end portion 72e of panel 72 and a free end portion 70e ofpanel 70; the panel subassembly is scored along lines 92 and foldedalong lines 92 to form the sleeve subassembly 86 seen in FIG. 11m;sleeve subassembly 88 is formed from panel 71 and 73 following steps11(a) through 11(n); and heat is applied to the exposed cement coating70d, 71d, 72d, and 73d and the sleeve subassemblies are brought togetherin nesting interfitting fashion to form the final sleeve assembly 17 asseen in FIG. 11(p).

In the final sleeve assembly, the inner and outer faces as well as theupper and lower annular edges of the sleeve assembly are totally sealedby the vinyl layers 82 so that the sleeve assembly is virtually moistureimpervious; the auxiliary sheets 80 on the outer annular surface of thesleeve assembly coact with the outer sheets 75 of the outer panels toform a strong outer skin capable of withstanding substantial tensionloading; the inner auxiliary sheets 78 coact with the inner sheets 75 ofthe inner cardboard panels to provide a strong inner skin for the sleeveassembly capable of withstanding high compressive loading; and the seams94 between the abutting vertical end edges of the panels 70, 71, 72 and73 are staggered or circumferentially spaced around the circumference ofthe sleeve assembly to increase the structural rigidity of the sleeveassembly.

Note that score lines 92 are provided in circumferentially spaced pairsso that angled corner portions 96 are provided in each sleevesubassembly and four angled corner portions 96 are provided in the finalsleeve assembly.

The manner in which the vinyl sheet or skin 82 is back formed to thevarious panels is best seen in FIG. 12. Specifically, the panel ispositioned over a back forming die 97 and the vinyl sheet 82 is heatedin an oven and is positioned over the upper face of the panel whereaftervacuum is applied to the upper face of the die via channels 97a openingin cavities 97b underlying apertures 74 and 76 so as to suck the heatedsheet downwardly into firm compliance with the upper face of the panel,suck portions 82a into the apertures 74,77 to form a lining for theapertures, and suck portions 82b downwardly over the end edges of thepanel and around the inner or under face of the panel, following whichthe excess vinyl portions such as seen at 82c and 82d may be suitablytrimmed to provide the final vinyl covered panel construction includingan edge portion 82e extending around the inner face of the panel,including around the cutouts in the lower edge of the panel, and anannular border portion 82f on the inner face of the panel around theapertures 74 and 77.

It will be understood that the heated vinyl sheet 82 activates the heatactivated cement coating 72d so that the vinyl sheet is firmly andadhesively secured to the panel.

It will further be understood that the vinyl sheet 82 is stretchable toallow the sheet to be sucked downwardly into the aperture 74 and 77 andallow the sheet to be wrapped around the end edges of the panel so thatthe thickness of the vinyl coating on the panel varies depending uponthe extent to which the vinyl has been stretched to achieve its finaldisposition with respect to the panel.

It will further be understood that the apertures in the upper and loweredge portions of the various panels are arranged such that they aremutually aligned in the final sleeve assembly and, similarly, thecutouts in the lower edges of the various panels are arranged such thatthe cutouts are mutually aligned in the final sleeve assembly.

The final sleeve assembly, as seen in FIG. 11(p), may now be utilized incooperation with the pallet 14. Specifically, as the sleeve assembly 17is lowered into position over the pallet 14, the leg portions of thesleeve assembly, formed by the joined leg portions 70b, 71b, 72b, 73b ofthe individual panels, fit respectively into the hollow legs of thepallet and rest on the bottom walls of the pallet legs; the cut out edgeportions of the sleeve assembly, formed by the joined cut out edgeportions 70c, 71c, 72c, 73c of the individual panels, fit into and restagainst the bottom edges of the groove means 40 with the apertures 77aligned with the latch members 46 of the respective latch assemblies;and the angled corner portions 96 of the sleeve fit conformingly intoand against angled rim corner portions 42b so that the angled rim cornerportions of the pallet embrace the outer surfaces of the lower edgeportions-of the angled corner portions of the sleeve assembly.

Following placement of the sleeve assembly into the pallet, the latchmembers 46 may be moved outboard, utilizing handles 46b, to pass theoutboard tips of the latch members through the apertures 77 and precludeinadvertent separation of the sleeve assembly from the pallet.

The seating of the lower edges of the leg portions of the sleeveassembly on the bottom walls of the pallet legs also has the desirableeffect of transferring compressive loads from stacked containersdirectly to the base or support surface for the container, as explainedmore fully in U S. Pat. Nos. 4,550,830 and 4,765,252 assigned to theassignee of the present application.

As best seen in FIG. 5, the thickness of the sleeve assembly, as definedby the combined thicknesses of panels 70,72 and 71,73, as augmented byauxiliary panels 78,80 and vinyl sheets 82, approximates the thicknessof the groove means 40 at the bottoms of the groove means so that thecutout edges 70c, 71c, 72c, 73c of the sleeve assembly fit snugly in thegroove means to preclude unwanted lateral movement of the sleeveassembly relative to the pallet.

Following the loading of the container with a suitable bulk material,lid 16 is placed over the upper edge of the sleeve assembly with theupper edge of the sleeve assembly fitting snugly in groove 60, includingfitting of angled corner portions 96 into and against angled lid cornerrim portions 58b, whereafter the latch members 46 of the latchassemblies of the lid may be moved outwardly in detenting fashion tomove the latch members into the aligned apertures 74 and precludeinadvertent removal of the lid from the container. It will be understoodthat the lid acts to constrain the upper circumferential edge of thesleeve assembly against outward, bulging movement in response to thepressures generated by the stored bulk materials but that, due to theburst strength of the sleeve assembly, the container may be fully loadedwith bulk material with the lid removed without fear of bulging of theupper edge of the sleeve assembly so that the container may, if desired,be loaded, transported, stored and the like without lid 16 in place.

An alternate methodology for performing the invention sleeve assembly isillustrated in FIGS. 13-21. The alternate methodology of FIGS. 13-21provides precise definition for the creases at the corners of the sleeveand allows the sleeve to readily assume a flat folded configuration forpurposes of storage and return shipment of the sleeve.

In the methodology of FIGS. 13-21, the four panels 70-73, afterreceiving the auxiliary cardboard sheets 78,80 and the vinyl layers 82as described With reference to FIG. 11, are adhesively secured togetherin staggered fashion to form a single flat panel assembly 100.

The flat panel assembly 100 is then placed in a press 102 with theassembly resting on die bars 104 supported and secured in longitudinallyspaced location along a lower platen 106 supported on the bed 108 of thepress. Each die bar is configured to define a pair of creases in thepanel assembly 100 extending across the entire width of the panelassembly from top edge to bottom edge. The die bars accordingly have alength at least equal to the width of the panel assembly.

The die bars are formed of a suitable ferrous material and each include,as viewed in FIG. 14, a left portion 104a and a right portion 104b. Eachportion defines a relatively shallow face 104c and a relatively steepface 104d with each shallow face 104c and each steep face 104dinterconnected by a radiused surface 104e. The shallow faces 104c mayfor example form an angle α of 25° with the horizontal; the steep faces104d may form an angle β of 45° with the horizontal; the radiusedsurfaces 104e may be formed by circles 104f having a diameter of 0.625inches; the center lines of the circles 104f may be spaced a distance oftwo inches; the width of the die bar between side edges 104g may be fiveinches; and the total height of the die bar may be 1.25 inches.

Die bars 110 are secured to the lower face 112a of the upper platen 112of the press in longitudinally spaced relation corresponding to thelongitudinally spaced relation of the die bars 104 on the lower platen.Die bars 110 are identical to die bars 104 with the exception that theyare inverted with respect to the die bars 104 and have a somewhatgreater height than the die bars 104. As with the die bars 104, thesteep faces 110d of the die bars 110 form an angle β of 45° with thehorizontal; the shallow faces 110c form an angle α of 25° with thehorizontal; the radiused surfaces 110e are defined by circles 110fhaving a diameter of 0.625 inches; the centers of circles 110f areseparated by a distance of 2 inches; and the die bars have a widthbetween side edges 110g of 5 inches. Die bars 110 may have a height of2.5 inches.

As shown, die bars 110 are positioned in precise vertical alignment withthe respective die bars 104 so that the radiused surfaces 104e definedby a die bar 104 respectively confront the radiused surfaces 110e of thecorresponding die bar 110. With this arrangement, and as best seen inFIG. 15, as the upper die bars 110 are lowered by lowering of the head114 of the press, the panel assembly 100 is selectively crushed betweenthe die bars 110 and 104 with each vertically aligned pair of die bars104 and 110 coacting to define a pair of parallel creases 110a in theupper or outer face 100b of the panel assembly defining a hinge section100j therebetween, and a corresponding pair of parallel creases 100c inthe lower or inner face 100d of the panel assembly defining a hingesection 100k therebetween. The creases are provided by crushing andflattening the flat and corrugated sheets 75,76 of the cardboard panelswith the total crush reducing the panel assembly 100 to a thickness ofless than 1/2 of its normal or original thickness. For example, if thepanel assembly 100 is formed by two corrugated triple wall cardboardpanels of 0.625 inches thickness for a total panel assembly thickness of1.25 inches, the crushed thickness of the panel assembly, as measuredbetween radiused surfaces 110e and 104e, may be 5 inches.

Each crease 100a, 100c formed respectively in the upper and lower faceof the panel assembly will be seen to have a configuration generallycorresponding to the configuration of the combined faces 110c, 110d and110e of 104e of the die bars 104 except that all of the length of faces110c, 110d and 104c, 104d are not duplicated in the creases. However,because of the different angles of the faces of the die bars, thecreases 100a include a relatively long face 100e and a relatively shortface 100f and the creases 100c include a relatively long face 100g and arelatively short face 100h. Since faces 104c and 104d, as well as faces110c and 110d, define an included angle of 110° it will be seen that thefaces 100e, 100f of the creases 100a and the faces 100g, 100h of thecreases 100c also define an included angle of approximately 110° so thateach pair of creases on each face of the panel assembly together definean included angle of 220°.

Following the creasing operation utilizing the press 102, the panelassembly is suitably folded to form the sleeve assembly seen in FIG. 17with the overlapping end sections 100m and 100n of the panel assembly100 secured together by a suitable adhesive. As best seen in FIG. 18,the creases 100a, 100c allow the panel assembly to readily assume thecorner configuration seen in FIGS. 17 and 18. In the cornerconfiguration, it will be seen that the creases 100c on the inside ofthe sleeve have closed up considerably but still define an angle betweenfaces 100g, 100h and that the creases 100a on the outer face of thesleeve have flattened considerably and have a shallow configuration.

The creases 100a, 100c also and importantly allow the sleeve to befolded totally flat for purposes of storage and shipment. The collapsedor flattened configuration of the sleeve is seen in FIGS. 19 and 20.With particular reference to FIG. 20, it will be seen that the creases110a and 110c allow the sleeve to be readily folded through 180° so asto allow the sleeve to assume a totally flat configuration with thecreases 100c on the inner side of the sleeve substantially totallycollapsing to allow the 180° folding of the sleeve and with the creases110a on the outside of the sleeve essentially disappearing.Specifically, the total 220° included angle defined by a pair of creases102c allows the sleeve to be folded readily through 180° at selectedcorners and the relatively long dimension of the outboard crease faces100g as compared to the relatively short dimension of the inboard creasefaces 100h allows the outboard faces 100g to extend, in the foldedconfiguration seen in FIG. 20, inwardly beyond the inner ends of thefaces 100h so as to allow the inner faces 100d of the adjacent sectionsof the panel assembly to assume an essentially flat, contiguous relativerelationship so as to further facilitate the total, flat folding of thesleeve. The folding of the sleeve is further facilitated by the partialcrushing of the hinge sections 100k between adjacent creases 100c sothat the hinge sections assume a relatively rounded or humpedconfiguration, as seen in FIG. 20, as compared to the plateauconfiguration seen in FIG. 16. The folding of the sleeve is furtherfacilitated by the creases 100a in the outside face of the sleeve whichact to facilitate the thinning out and elongating of the outer panel toallow the outer panel to wrap readily around the inner panel in thecollapsed or folded configuration of the sleeve.

The described creasing arrangement not only allows the sleeve to bereadily collapsed to a flat configuration, it also avoids a thickeningor swelling of the sleeve at the collapsed corners. Specifically, in theillustrated embodiment, the thickness of the folded sleeve isapproximately 21/2 inches and this thickness extends for the entirelength of the collapsed sleeve rather than increasing or swelling at thecollapsed corners to a dimension substantially in excess of 21/2 inches.Being able to hold a constant thickness for the collapsed sleeve throughits entire length allows the sleeve to be stacked in multiple layerswith each collapsed sleeve resting firmly and totally on the underlyingsleeve with no space therebetween and with each sleeve occupying, in thestack, only 21/2 inches.

It should also be understood that the distance between the center linesof circles 104f, 110f (2 inches in the disclosed embodiment), the lengthof the long crease faces 100e, 100g as compared to the length of theshort crease faces 100f, 100h, and the angles of the various creasefaces (as determined by the angles α and β of the die bars) are allcritical, on a comparative basis, to allowing the sleeve to readilycollapse and to ensuring that the collapsed sleeve is not thickened orswollen at the collapsed corners.

The invention container, although formed from inexpensive cardboard andplastic materials in a relatively inexpensive process, provides acontainer having extremely high sidewall strength, so as to be eminentlysuitable for use in storing bulk materials, and having a virtuallymoisture impervious construction, so as to enhance its durability andallow outdoor use and storage. The sealed aspect of the sleeve alsoprecludes entry of contaminants, such as food particles, into the flutesof the cardboard structures so as to enhance the usability andreusability of the invention container in applications, such as foodhandling, where sanitation is important, and the unique methodology forforming specific creases at specific locations along the sleeve allowsthe sleeve to be folded totally flat for purposes of storage andshipment despite the rather bulky aspect of the sleeve due to itscomposite wall construction.

Whereas the preferred embodiments of the invention have been illustratedand described in detail, it will be apparent that various changes may bemade in the disclosed embodiments without departing from the scope orspirit of the invention.

I claim:
 1. A container including a plastic pallet and a tubular sleeveremovably supported on the upper face of the pallet to form thecontainer, characterized in that the wall of the sleeve has a sandwichcross-sectional configuration including a plastic layer and a cardboardlayer firmly bonded together over substantially their entire confrontinginterface.
 2. A method of forming a container including a plastic palletand a tubular sleeve removably supported on the upper face of thepallet, said method comprising the steps of:forming a plastic pallet;providing a cardboard panel structure; bonding a plastic layer to atleast one side face of the panel structure to form a laminated panelstructure; forming creases in the laminated panel structure and foldingthe laminated panel structure at the creases to form the laminated panelstructure into a polygonal tubular sleeve with the bonded plastic layeron the outside of the sleeve; and positioning the sleeve on the upperface of the plastic pallet.
 3. A method of forming a container includinga plastic pallet and a tubular sleeve removably supported on the upperface of the pallet, said method comprising the steps of:forming aplastic pallet; providing a first outer strip of corrugated cardboardmaterial including flat inner and outer sheets and at least onecorrugated inner sheet; providing a second inner strip of corrugatedcardboard material including flat inner and outer sheets and at leastone corrugated inner sheet; securing the inner sheet of said first outerstrip to the outer sheet of said second inner strip to form a doublewall strip having exposed inner and outer faces, top and bottom edges,and a normal thickness equal to the combined thickness of said first andsecond strip; providing pairs of first and second parallel V-shapedcreases in at least one face of said double wall strip at longitudinallyspaced locations therealong and extending from the top to the bottomedge of said double wall strip, said pairs of creases defining side wallportions between pairs of creases having a length substantiallyexceeding the distance between the first and second creases of a creasepair; folding said double wall strip at said locations to form apolygonal sleeve having relatively short angled corner portions betweenthe first and second creases of each pair and relatively long straightside wall portions between each pair of creases; and positioning thesleeve on the upper face of the plastic pallet to form the container. 4.A method of forming a tubular sleeve for use with a pallet to form acontainer, said method comprising the steps of:providing a strip ofcrushable material; and providing pairs of parallel creases in at leastone face of said strip in longitudinally spaced locations therealongwith each crease including a relatively short inboard side wallintersecting a relatively long outboard side wall to form an includedangle and with the total included angle defined by the two creases of apair being at least 180° so that the strip may be folded at saidlocations and the free ends of the strip joined to form a polygonalsleeve and so that the strip may be folded back upon itself through 180°to collapse the sleeve into a flat configuration with the relativelylong outboard side walls of the creases extending beyond the relativelyshort inboard side walls of the creases to allow confronting portions ofthe sleeve on opposite sides of the crease to assume a contiguousrelationship to minimize the sleeve thickness for shipping and storage.5. A method of forming a tubular sleeve for use with a pallet to form acontainer, said method comprising the steps of:providing a first outerstrip of corrugated cardboard material; providing a second inner stripof corrugated cardboard material; securing one face of said first outerstrip to one face of said second inner strip to form a double wall striphaving exposed inner and outer faces, top and bottom edges, and a normalthickness equal to the combined thickness of said first and secondstrips; providing pairs of parallel creases in each outer face and ineach inner face of said double wall strip at longitudinally spacedlocations therealong with each crease extending from the top to thebottom edge of said double wall strip and with each crease in said outerface confronting a crease in said inner face and coacting with thatconfronting crease to define a crushed area therebetween of reducedthickness; and folding said double wall strip at said locations to forma polygonal sleeve having angled corner portions between the creases ofeach pair and straight side wall portions between each pair of creases.6. A method according to claim 5 wherein:said reduced thickness is lessthan half of said normal thickness.
 7. A method according to claim 5wherein:each crease is defined by converging sidewalls defining anincluded angle therebetween and the total included angle defined by thetwo creases in each pair is at least 180° so as to allow the strip to befolded flat upon itself.
 8. A method of forming a tubular sleeve for usewith a pallet to form a container, said method comprising the stepsof:providing a strip of crushable material; and providing pairs ofparallel creases in each face of said strip at longitudinally spacedlocations therealong with each crease in one face confronting a creasein the other face and coacting with that other crease to define acrushed area therebetween of reduced thickness and with each creaseincluding two intersecting side walls forming an included angle and withthe total included angle defined by the two creases of a pair being atleast 180° so that the strip may be folded at said locations and thefree ends of the strip joined to form a polygonal sleeve and so that thestrip may be folded back upon itself to 180° through collapse the sleeveinto a flat configuration for shipping and storage.
 9. A methodaccording to claim 8 wherein:said reduced thickness is less than half ofthe original thickness of said strip.